Novel Targeted Therapy for Precursor B-Cell Acute Lymphoblastic Leukemia: Anti-CD22 Antibody-MXD3 Antisense Oligonucleotide Conjugate

Abstract

The exponential rise in molecular and genomic data has generated a vast array of therapeutic targets. Oligonucleotide-based technologies to down regulate these molecular targets have promising therapeutic efficacy. However, there is relatively limited success in translating this into effective in vivo cancer therapeutics. The primary challenge is the lack of effective cancer cell-targeted delivery methods, particularly for a systemic disease such as leukemia. We developed a novel leukemiatargeting compound composed of a monoclonal antibody directly conjugated to an antisense oligonucleotide (ASO). Our compound uses an ASO that specifically targets the transcription factor MYC-associated factor X (MAX) dimerization protein 3 (MXD3), which was previously identified to be critical for precursor B-cell (preB) acute lymphoblastic leukemia (ALL) cell survival. The MXD3 ASO was conjugated to an anti-cluster of differentiation-22 (CD22) antibody (αCD22 Ab) that specifically targets most preB ALL. We demonstrated that the αCD22 Ab-ASO conjugate treatment showed MXD3 protein knockdown and leukemia cell apoptosis in vitro. We also demonstrated that the conjugate treatment showed cytotoxicity in normal B cells, but not in other hematopoietic cells, including hematopoietic stem cells. Furthermore, the conjugate treatment at the lowest dose tested (0.2 mg/kg Ab for 6 doses -twice a week for 3 wks) more than doubled the mouse survival time in both Reh (median survival time 20.5 versus 42.5 d, p < 0.001) and primary preB ALL (median survival time 29.3 versus 63 d, p < 0.001) xenograft models. Our conjugate that uses αCD22 Ab to target the novel molecule MXD3, which is highly expressed in preB ALL cells, appears to be a promising novel therapeutic approach.

Novel targeted therapy for neuroblastoma: silencing the MXD3 gene using siRNA

“…Frozen whole cell pellets were prepared for western blotting as described previously ( 11 ). Briefly, cell pellets were denatured and boiled, run on a 4–20% Tris-Glycine SDS-PAGE gel, and transferred to a nitrocellulose membrane using a wet transfer system.…”

“…Since monotherapy does not work for most cancers, an ideal therapy should include multiple molecular-targeted approaches. Previously, we identified the transcription factor MXD3 as a novel target for precursor B-cell acute lymphoblastic leukemia (preB ALL) ( 9 – 11 ). MXD3 is a member of the family of Mad proteins that interact with Max proteins ( 12 ) and is reported to play a role in medulloblastoma tumorigenesis ( 13 ).…”

Antibody Conjugates-Recent Advances and Future Innovations

“…Additionally, intramuscular injection enabled superior levels of target engagement in a model of peripheral artery disease, with muscular regeneration due to myostatin knockdown observed with microgram-scale injections. While this Fab'-based study utilized structural cystines for conjugation, other therapeutic antibody-oligonucleotide conjugation systems not yet described in this section have been reported, including two oncology examples which applied two-step conjugations for azide-labeling the antibody which were then treated with cyclooctyne-appended ASOs to generate the conjugates [121,122]. Other antibody-oligonucleotide conjugation methods beyond the scope of this review (i.e., for immuno PCR applications, pre-targeted radiotherapy, or those which utilize non-covalent heterogeneous complexes) have been recently reviewed [109].…”

Drug discovery and therapeutic delivery for the treatment of B and T cell tumors

“…Recent research efforts have focused on new cellular surface targets like CD27 44 and EphA3 61 , as well as improving cancer eradication though development of antibody drug conjugates for CD22 62 . Anti-CD22 antibody therapies have arguably been the most successful, and clinically translatable in treating ALL and other leukemias and lymphomas.…”

“…Since upon binding with CD22, the antibody therapy is endocytosed, CD22 antibodies are an intriguing drug delivery platform for drugs with intracellular actions. Satake et al used monoclonal anti-CD22 antibodies to traffic antisense oligonucleotides for inhibiting translation of MYC-associated factor X (MAX) dimerization protein 3 (MXD3), an important transcription factor involved in preB-cell acute lymphoblastic leukemia 62 . Results of their preclinical study showed that the conjugate successfully trafficked the oligonucleotides to the leukemia cells without off target effects and at one-twentieth of the dose required for similar effects from anti-CD22 monoclonal antibody therapy alone 6263 .…”